A popular device for handling large amounts of information in a data processing system is the data storage library. These libraries store and manage large numbers of data cartridges, typically containing magnetic tape on which data is recorded. A data storage library is comprised of arrays of storage cells, each cell being formed to contain a single data cartridge. The arrays each hold a plurality of data cartridges, and each data cartridge has some kind of identifying information, such as a label or bar code. Typically, the arrays surround a robotic arm which has an optical system for selecting cartridges, and is operable to locate a particular storage cell and retrieve and transport a data cartridge therefrom. The storage cells preferably have exact dimensions that correspond to the size of the cartridges, since the cartridges must be positioned in a precise manner if the robotic arm is to grasp them correctly.
Different hardware manufacturers have independently developed data cartridges that are unique to each manufacturer. Accordingly, the owner of a data storage library may wish to use a variety of different cartridge types within a single library system. However, it has traditionally been a problem in library design to accommodate data cartridges of different sizes into the same library enclosure. For instance, if a single size storage cell is used for storing data cartridges of different sizes, the robotic arm may have difficulty transferring a cartridge due to misalignment of the cartridge within its storage cell. Alternatively, a fixed number of storage cells sized for each different type of cartridge may be provided within the data storage library. However, this solution is undesirable since each library must be specially customized with fixed numbers of storage cells corresponding to the owner's needs, and those needs may change over time.
Therefore, a need exists for a data storage library which may be easily adapted to accommodate cartridges of different sizes, such that library users may modify their distribution of different cartridge types and still retain their investment in their library systems.